Linear drive

ABSTRACT

A linear drive comprising a housing having a tube body ( 3 ) and a terminally mounted housing cover ( 4 ). In the wall of the tube body ( 3 ) a cavity is located, into which a sensor ( 14 ) extends. The rear end section ( 21 ) of the sensor ( 14 ) is in a socket ( 18 ), arranged as an extension of the cavity, of the housing cover ( 4 ). This socket ( 18 ) is formed by a recess ( 22 ) and its opening ( 26 ) extends from the end face ( 23 ) facing the tube body ( 3 ), of the housing cover ( 4 ) as far as the adjacent lateral outer face ( 24 ) of the housing cover ( 4 ). The electrical lead means for the sensor ( 14 ) are associated with the lateral section of the recess&#39;s opening ( 26 ).

[0001] The invention relates to a linear drive comprising a housinghaving a tube body containing a receiving space for a linearly movingdrive part and a housing cover mounted on an end side of the tube body,a peripherally closed cavity formed in the wall of the tube body, whichcavity is open toward the tube body's end face facing the housing cover,and at least one socket, which is provided as an axial extension of thecavity on the housing cover and also provided for the rear end sectionof a sensor serving for detection of at least one position of the drivepart, said sensor extending from the socket into the cavity in the tubebody.

[0002] A linear drive of this type is described in the German patentpublication 4,306,539 C2. In this known case the tube body possesses achannel-like cavity, formed the wall thereof and aligned with a socket,in the form of a receiving hole, in the housing cover mounted at theend. The sensor is designed in the form of rod and is plugged from therear side of the housing cover through the receiving hole into thecavity in the tube body, the rear end section of the sensor being fixedin the receiving hole. At the rear end section of the sensor electricalleads are provided and associated with the rear side (opposite to thetube body) of the housing cover whence same make possible electricalcontact and connection with the sensor.

[0003] In the case of linear drive the measure necessary for the holdingin place of the sensor on the housing cover take up a relatively largespace in the longitudinal direction of the linear drive. Sameaccordingly has a relatively large overall length. Therefore it is oneobject of the present invention to create a linear drive, which whileproviding for secure holding of the sensor in place has a small overalllength.

[0004] In order to achieve this object there is a provision such thatthe socket is constituted by a recess in the housing cover, the openingof such recess extending from the end face, facing the tube body, of thehousing cover continuously as far as the adjacent lateral outer face ofthe housing cover, the electrical lead means of the sensor beingassociated with the lateral section of the recess's opening.

[0005] It is in this manner that the rear end section of the sensor isseated in a recess, extending along a corner of the housing cover, theelectrical contact with the sensor being possible from the side of thehousing cover. The length, as measured in the longitudinal direction ofthe linear drive of the recess may be made relative short, somethingwhich means short dimensions of the housing cover and provides spacewithin the housing cover for other means, which are necessary for theoperation of the linear drive. Since the electrical lead means of thesensor are associated with the lateral section of the recess's opening,satisfactory accessibility is provided for. Finally it is also possibleto ensure unloseable fixation of the sensor in place, sincedeinstillation is only possible by removal of the housing cover, thispreventing unauthorized access.

[0006] Further advantageous developments of the invention are defined inthe dependent claims.

[0007] It is preferred for the rear end section of the sensor to be inthe form of an attachment section, by way of which the sensor is so heldin the recess, that, as considered in the state with the tube bodyremoved, it extends firmly held in a transverse position, that is to sayit is secured in the transverse direction and practically incapable ofmovement, extending away from the housing cover. Therefore when mountingthe sensor in place it is possible to firstly secure same with theattachment section in the recess in the housing cover in order in thecourse of later fixing of the housing cover on the tube body tosimultaneously insert outwardly extending longitudinal section of thesensor into the cavity.

[0008] It is particularly advantageous for the rear end section of thesensor to be designed in the form of an attachment section, whichrenders possible plugged mounting of the sensor in the recess. In thiscase a design of the plug connecting means is preferred such that thedirection of plugging coincides with the longitudinal direction of thelinear drive.

[0009] The plug connecting means may for example be constituted bywells, which extend in the direction of plugging on the housing cover,such recesses being provided in the lateral faces of the recess and bylateral projections, fitting in the wells, of the sensor. Furthermore areversed association of the plug connecting means would be possiblehere.

[0010] A design is preferred such that the sensor has its one attachmentsection held immovably in the axial direction between the housing coverand the tube body. It is in this manner that an exact, axially securedpositioning of the sensor in relation to the housing of the linear driveis ensured without additional attachment means. This is for instancemade possible by having the attachment section and the recess so matchedin their dimensions that the sensor is proud of the tube body to a smallextent when housing cover is not mounted on the tube body so that in themounted state of the housing cover the tube body is acted upon by thefacing end side of the tube body.

[0011] It is convenient for the recess to be closed, apart from theopening thereof extending from the end face as far as the lateralexternal face.

[0012] Preferably no fixation of the sensor's longitudinal section,extending into the cavity in the tube body, is required so thatconsequently the sensor is conveniently free right from the housingcover along its full length where it projects into the cavity of thetube body and apart from its rear end section is not fixed anywhere. Atthis point it is to be noted as well that the axial overall length ofthe sensor's longitudinal section extending into the cavity ispreferably selected to be less than the overall length of the tube body,it being sufficient for the sensor to extend so far into the cavity thatthe part is covered or the point is reached, which is to be detected.

[0013] Preferably the cavity extends along the full overall length ofthe tube body and opens at the opposite end faces of the tube body. Ifhousing covers are provided on both ends of the tube body and suchhousing covers have a recess with an associated sensor, it isaccordingly possible for both sensors to extend from opposite sides intoone and the same cavity.

[0014] Since the sensor may readily be so designed that the section ofits length extending into the cavity does not require any transversesupporting action, the cross sectional shape of the cavity does not haveto meet any special requirements and practically any design is possible.This means that the cross sectional shape of the cavity may be adaptedto comply with other features of the tube body. It is for instancepossible to have a tube body in the form of a extrude, which in its wallhas a plurality of axially continuous channels distributed about theperiphery of the receiving space, such channels being provide to saveweight and material, one of such channels being utilized as a cavity toreceive the sensor.

[0015] It is preferred for the electrical lead means of the sensor to bedesigned in the form of plug means so that a cable may be replaced asdesired. Furthermore the sensor preferably has an essentially L-likeshape, the longer limb extending into the cavity of the tube body whilethe shorter limb is provided on the rear end section and extends throughthe laterally aligned section of the recess's opening to the outside. Inthis case the electrical lead means are preferably provided on theshorter L limb of the sensor.

[0016] The sensor may be provided with light producing display means onthe rear end section, such display means making it possible to indicatethe operational state of the sensor. In this connection in the case of aparticularly economic structure there may be such a provision that thesensor has a housing which is transparent at least at the rear endsection, through which housing the light signals from the light displaymeans are visible from the outside. Accordingly the light producingdisplay means may be readily seen while the display area protected in anoptimum manner.

[0017] The design in accordance with the invention is more particularlyadvantageous in the case of linear drives operated using fluid power.However, the invention is also applicable to linear drivess, which areoperated with other types of energy, as for example electric power.

[0018] In the following the invention will be described with referenceto the accompanying drawings.

[0019]FIG. 1 shows a first design of the linear drive in accordance withthe invention in perspective.

[0020]FIG. 2 shows a section of the linear drive of FIG. 1, which islimited to the representation of the part of the tube body and of thetube body and a rear housing cover, the components being illustrated inan exploded view.

[0021]FIG. 3 shows housing cover of the linear drive in accordance withFIGS. 1 and 2 in a separate view with the sensor secured thereto.

[0022]FIG. 4 shows an end-on view of the arrangement of FIG. 3 lookingin the direction of the arrow IV.

[0023]FIG. 5 is an end-on view of the arrangement of FIG. 2 looking inthe direction of the arrow V.

[0024] The drawings show a fluid power operated linear drive 1, whichpossesses an elongated housing 2, a tube body and housing covers 4mounted of the two ends of the tube body 3 permanently.

[0025] In the interior of the housing 2 a preferably cylindricalreceiving space 5 is provided, which extends in the longitudinaldirection of the housing 2 and which is delimited at the externalperiphery by the wall 6 of the tube body and at the end by the twohousing covers 4.

[0026] A drive part 7 is provided in the receiving space 5 and thisdrive part 7 is in the form of a piston in the case of a fluid powerversion of the linear drive and is able to move inthe receiving space 5in the direction of the longitudinal axis 8 of the housing. The drivepart 7 divides the receiving space 5 axially into two working chambersinto which a respective fluid duct 12 (running in the adjacent housingcover 4) opens and by way of such fluid duct the associated power ductmay be supplied with fluid power medium, as for example compressed air,or may be depressurized or, respectively, vented. This means that thedrive part 7 may be caused to perform a linear movement in the directiondefined by the longitudinal axis 8 of the housing, and such motion maybe transmitted to a transmitting part 13 or dog outside the housingengaged with the drive part 7.

[0027] Said transmitting part 13 is, in the present working example, inthe form of a piston rod extending through the front housing cover 4, itmaking sliding engagement with such front housing cover so thataccordingly the corresponding housing cover 4 may be termed a bearingcover. The opposite, rear housing cover 4 is in the form of a plainterminal cover.

[0028] In the case of an alternative design (not illustrated), thelinear drive is in the form of a rod-less linear drive so that bothhousing covers 4 act as terminal housing covers and the transmission ofpower between the drive part 7 and the transmitting part 13 takes placein some other manner, for example by magnetic force or by means of a dogextending through a longitudinal slot in the housing 2.

[0029] In the case of a further design, not illustrated, of the lineardrive as an electrical drive the drive part 7 is operated by electricalenergy, for instance using a lead screw drive.

[0030] The linear drive 1 is provided with a position detecting means,which renders it possible to detect a plurality of positions assumed bythe drive part 7 in relation to the housing 2. In the case of suchpositions to be detected it is for example a question of terminalpositions of the drive part 7 as defined by the maximum stroke of thedrive part 7. This system includes a respective sensor 14 for the twoaxial end parts of the housing 2, such sensor being able to respond,without making physical contact, to an actuating element constituted bythe drive part 7 or provided therein, when such actuating element, inthe course of its linear motion, assumes a position near suitabledetection means 15 for the sensor 14 and more especially assumes such aposition that it is radially opposite the detection means 15 on theinside thereof.

[0031] The actuating element may for instance be in the form of apermanent magnet and the sensor 14 may be a so-called reed switch, inthe case of which the detection means 15 are operated by the magneticfield of the actuating element.

[0032] The arrangement and design of the two sensors 14 is identical inthe present working example so that the following detailed account isonly in relation to the sensor 14 which is associated with the rearhousing cover 4. The description therefore applies also for the sensorprovided on the front housing cover 4, it being necessary to mentionthat the linear drive 1 may be designed so that a sensor is providedonly on one housing cover and each housing cover may be provided withseveral sensors.

[0033] The respective sensor 14 is provided with a cavity 16 in the wall6, which peripherally delimits the receiving space 5, of the tube body3, such cavity 16 preferably extending in the longitudinal direction ofthe tube body and being entirely enclosed in the peripheral direction.Such cavity 16 opens at the end face, herein termed the first end face17, of the tube body, on which the housing cover 4 is mounted. With aview to simplifying manufacture the cavity 16 extends along the fulloverall length of the tube body 3 and opens at its opposite end faces.This means that it is possible to have a tube body 3 in the form of anextrude in whose wall 6 one or more axially continuous channels 19extend which are distributed about the periphery of the receiving space5 and of which one is utilized as a cavity 16.

[0034] As an axial extension of the cavity 6 a socket 18 is provided forthe rear end section 21 of the sensor 14. This socket 18 is constitutedby a recess 22 in the housing cover 4, which is placed like a cutting inthe transitional area between the end face (in the following termed thesecond end face 23) of the housing cover 4 and the lateral outer face 24in the housing cover 4, such face 24 facing radially outward in relationto the housing's longitudinal axis 8. Since the second end face 23merges with the lateral outer face 24 at a surrounding edge 25, whichdependent of the design may be sharp or blunt, it is possible to saythat the recess 22 severs the edge 25 and in effect constitutes a recessextending along a corner. The recess's opening 26, which defines thetransition to the second end face 23 and the lateral outer face 24 thusthe tube extends from the second end face 23, which is turned toward thebody 3, continuously as far as the adjacent lateral outer face 24, ithaving a first opening section 27 opening at the second end face 23 anda second opening section 28 opening at the lateral outer face 24. Theseopening sections 27 and 28 merge with each other continuously, i. e.without interruption.

[0035] The sensor 14 is an elongated component and in the workingexample possesses an essentially L-like shape. The transitional zonebetween the longer limb 32 and the short limb 33 here defines the rearend section 21 of the sensor 14. In the working embodiment illustratedthe same is in the form of an attachment section 34, by way of which thesensor 14 is fixed in the recess, it having its longer limb 32projecting out of the first opening section 27 having its shorter limb33 extending out of the second opening section 28 of the recess 24. Thelonger limb 32 here extends in parallelism to the housing's longitudinalaxis 8 and extends into the associated cavity 16, whose opening,provided at the first end face 17, is aligned with the first openingsection 27, provided at the second end face 23 of the housing cover 4,of the recess 22.

[0036] The above mentioned detection means 15 are located in the longerlimb 32, with which same are preferably integrated. They are internallyconnected with electrical lead means 35 for the sensor, which serve formaking an electrical contact and are arranged in the lateral, secondsection 28 of the recess's opening 26. In the working embodiment theelectrical lead means 35 are provided on the shorter limb 33 and arepreferably in the form of plug means, which render possible a detachableconnection with electrical leads for the connection of other equipment,for instance in the form of a cable. It would be feasible to haveelectrical leads in the form of fixed conductors or electrical leadmeans in the form of wireless signal transmitting means or as forinstance infrared transmission means or using radio waves.

[0037] In the mounted state the sensor 14 is consequently seated so thatits rear end section 21 fits into the recess 22, whence it extend intothe associated cavity 16 in the tube body 3 and whence the electricalcontact making means extends outward to the side. Removal of the sensor14 is only possible after firstly removing the housing cover 4,something which prevents tampering. Furthermore, the locking of theattachment section 34 in the recess 32 ensures a permanent exact settingof the axial position of the sensor 14 and accordingly the detectionmeans 15 provided on same. Without complex adjustment it is thuspossible to set the position of the sensor 14 as part of assembly workby the manufacturer of the linear drive. Here there is the possibilityof making available several sensors 14 which are different as regardstheir axial overall length and, respectively, the axial position of thedetection means 15 so that customization may include the mounting of asensor, which exactly corresponds to the relevant position of the drivepart 7. In this respect it would also be possible to so design thedetection means 15 that same are suitable for detecting a plurality ofpositions.

[0038] Preferably the attachment section 34 of the sensor 14 is soadapted to the configuration of the recess 22 that when same is mountedin the recess 22 it is held in the recess 22 even when housing cover 4is not yet installed on the tube body 3. This opens up the possibilityof prefixing the sensor 14 on the housing cover 4 and during followingfitting of the housing cover 4 automatically positioning the sensor 14in place.

[0039]FIG. 3 shows the housing cover 4 removed from the tube body 3 andwith the sensor 14 fitted in the recess 22, the sensor 14 being so heldin the recess 22 that it is firmly held in the transverse position, thatis to say practically immovably held in the transverse position, and itextends away from the housing cover 4.

[0040] The consequence of this is that with the housing cover 4 mountedon the tube body 3, the sensor 14 has its entire length in the tube bodyso that it is practically free on all the sides in the cavity 16 andapart from the attachment section 34 is not fixed to the housinganywhere. This means that adaptation of the cross sectional shape of thecavity 16 to that of the length section, projecting in the cavity 16, ofthe sensor 14 is unnecessary. The sole condition as regards the shape ofthe cavity 16 is that same should render possible insertion of thesensor 14. It is in this manner that it is generally possible to usereadily available extruded tubular material for the tube body 3, thecross sectional shape of the longer limb of the sensor 14 being sodesigned that insertion into the channels 19 in the wall 6 of the tubebody 3 may be undertaken without any trouble.

[0041] It is convenient for the attachment section 34 of the sensor 14to be so designed that it is able to be fixed in position by plugging inthe recess 22. The arrangement is then preferably such that thedirection 36 of plugging indicated by the double arrow in FIG. 3 is at aright angle to the second end face 23 of the housing cover 4.

[0042] The plug means 37 rendering possible the plug connection arepreferably so designed that they only allow one degree of freedom forthe sensor 14 in the direction 36 of plugging, whereas all other degreesof freedom are locked. This means that more particularly it isimpossible for the plugged in attachment section 34 to be removed pastthe second section 28 of the recess 22 or to be turned about itslongitudinal axis. Such a secure fixation in place furthermore ensuresan exact position with correspondingly exact detection.

[0043] In the working embodiment the plug connection means 37 areconstituted by groove-like wells 38 running in the plugging direction 36on sides of the recess 22, such wells being located on the two mutuallyopposite side faces 42 of the recess 22. These side faces 42 lie inplanes, which run at a right angle to the second end face 23 and at thesame time extend athwart the lateral outer face 24. The wells 38 open atthe second end face 23 and extend approximately along the length, asmeasured in the plugging direction 36, of the recess 22.

[0044] The plugging means 37 provided on the attached section 34 areformed by laterally projecting and for example rib-like projections 43,which also run in the plugging direction 36 and which on insertion ofthe sensor 14 fit into the wells 38. It will be clear that thearrangement may also be reversed so that the projections are located onthe lateral wall of the recess 22 and the wells 38 are in the lateralface of the attachment section 34.

[0045] The depth of insertion, as measured in the plugging direction 36,of the attachment section 34 may be preset by having a matching lengthof the plugging connection means 37. Preferably, however the limitationof the depth of insertion is by the rear delimiting face 44, of therecess 22 opposite the first opening section 27 in the pluggingdirection 36, against which face 44 the inserted sensor rests on therear face 45 of the attachment section 34. Here it is an advantage forthe rear delimiting face 44 of the recess 22 to have a concave shape asillustrated and for the rear side 45 of the attachment section 34 to beconvex and complementary thereto.

[0046] The sensor 14 can be secured in the desired position withoutusing specially adapted attachment means, that is to say simply by thecooperation with the housing cover 4 and the tube body 3. For thispurpose the shape and the overall length of the attachment section 34and of the recess 22 may be so matched that in the position insertedinto the recess 22 but before mounting the housing cover 4 on the tubebody the attachment section 34 slightly projects past the zones of thesecond end face 23 adjacent to the recess 22. The correspondinglyprojecting part of the attachment section 34 is depicted in FIG. 3 at46. If now the housing cover 4 is mounted on the tube body 3 and isclamped to same, for example using attachment screws 47 or otherattachment means, axially, the projecting part 46 will be acted upon bythe first end face 17 of the tube body 3. As a result the sensor 14 willhave its attachment section 34 clamped in an axially immovable fashionbetween the housing cover 4 and the tube body 3.

[0047] In the case of this type of attachment manufacture of theattachment section 34 of a material is preferred which possesses acertain degree of deformability, for instance a plastic material.Furthermore, the amount by which the part 46 stands proud is selected tobe relatively small. This means that the desired clamping effect isproduced and simultaneously a flush surface-to-surface contact of thetwo end faces 17 and 23 is ensured.

[0048] The recess 22 is preferably closed on all sides apart from therecess's opening 26 so that more particularly entry of foreign matter isprevented.

[0049] In order to indicate particular operational states of the sensor14 the sensor 14 is provided with light producing display means 48 atits rear end section 21, such means being for example one or more LEDs.Such LEDs are located in the interior of the sensor 14 and may bearranged on a printed circuit board, not illustrated in detail, whichcarries the detection means 15 and/or the other electronic componentsrequired for the operation of the sensor 14. In order nevertheless toensure good visibility of the LED signals, the housing 52 of the sensor14 is manufactured of a transparent material at least adjacent to theattachment section 34 and preferably entirely. It is in this manner thatit is possible for all functional parts of the sensor to be encapsulatedin a fluid-tight fashion without reducing the indicating effect thereof.

[0050] In the working embodiment the sensors 14 provided on the twohousing covers 4 extend into different cavities 16 in the housing 2. Itwill however be clear that a common cavity could be provided for allsensors 14, if this should be allowed by the overall length of thesensor section extending into the cavity.

[0051] Even in the case of a relatively short length of the recess 22,as measured in the direction of the housing's longitudinal axis 8, anextremely reliable fixation of the sensor 14 may be ensured. Theconsequence of this is that the housing cover 4 has an extremely shortoverall length, this leading to compact dimensions of the linear drive1. Moreover, the attachment means for the sensor 14 only occupy anextremely small fraction of the overall volume of the housing cover 4 sothat there is sufficient free space for the installation or integrationof further functional components in the housing cover 4. FIG. 1 showsfor example a set screw 53 arranged in an axial continuation of therecess 22 in the housing 4, for a speed regulating valve or for apneumatic damping means to slow down when approaching the terminalposition.

1. A linear drive comprising a housing (2) having a tube body (3)containing a receiving space (5) for a linearly moving drive part (7)and a housing cover (4) mounted on an end side of the tube body (3), aperipherally closed cavity (16) formed in the wall (6) of the tube body(3), which cavity (16) is open toward the tube body's (3) end facefacing the housing cover (4), and at least one socket (18), which isprovided as an axial extension of the cavity (16) on the housing cover(17) and also provided for the rear end section (21) of a sensor (14)serving for detection of at least one position of the drive part (7),said sensor (14) extending from the socket (18) into the cavity (16) inthe tube body (3), characterized in that the socket (18) is constitutedby a recess (22) in the housing cover (4), the opening (26) of suchrecess (22>) extending from the end face (23), facing the tube body (3),of the housing cover (4) continuously as far as the adjacent lateralouter face (24) of the housing cover (4), the electrical lead means (35)of the sensor (14) being associated with the lateral section (28) of therecess's opening (26).
 2. The linear drive as set forth in claim 1,characterized in that the rear end section (21) of the sensor (14) isdesigned in the form of an attachment section (34) by way of which thesensor (14) is so held in the recess (22) that as viewed after removalof the tube body (3), same extends in a firmly held transverse positionfrom the housing cover (4).
 3. The linear drive as set forth in claim 1or in claim 2, characterized in that the rear section (21) of the sensor(14) is designed in the form of an attachment means (34) by way of whichthe sensor (14) may be held in position in the course of assembly byplugging.
 4. The linear drive as set forth in claim 3, characterized inthat the attachment section (34) and the recess (22) are so providedwith cooperating plug connecting means (37) that the sensor (14) may beplugged in past the section (27), facing the tube body (3), of therecess's opening (26) into the recess (22) and in the plugged-in stateis held immovably in the position athwart the direction (36) ofplugging.
 5. The linear drive as set forth in claim 2, characterized inthat the plug connecting means (37) on the housing cover (4) areconstituted by wells (38) extending in the direction (36) of plugging inthe lateral faces (42) of the recess (22) and on the sensor (14) areconstituted by lateral projections (43) fitting into the well (38) orvice versa.
 6. The linear drive as set forth in any one of the claims 3through 5, characterized in that the sensor (14) is clamped at itsattachment section (34) in an axially immovable fashion between thehousing cover (4) and the tube body (3).
 7. The linear drive as setforth in claim 6, characterized in that when the housing cover (4) isnot mounted on the tube body (3) the attachment section (34) of thesensor (14) extends a small distance past the end face (23) facing thetube body (3), of the housing cover (4) and in the mounted state of thehousing cover (4) is acted upon by the facing end face (17) of the tubebody (3).
 8. The linear drive as set forth in any one of the claims 1through 7, characterized in that the rear delimiting face (44), which isopposite to the section (27) of the recess's opening (26) turned towardthe tube concrete, is concave in shape, the rear end section (21) of thesensor (14) having a convex shape which is complementary, of theassociated rear side (45).
 9. The linear drive as set forth in any oneof the claims 1 through 8, characterized in that apart from the recess'sopening (26) the recess is closed.
 10. The linear drive as set forth inany one of the claims 1 through 9, characterized in that starting at thehousing cover (4) the sensor (14) has its full length, which extendsinto the cavity (16), free on all sides and apart for its rear endsection (21) is not fixed at any point.
 11. The linear drive as setforth in any one of the claims 1 through 10, characterized in that thecavity (16) extends along the entire overall length of the tube body (3)and opens at opposite end faces of the tube body (3).
 12. The lineardrive as set forth in any one of the claims 1 through 11, characterizedin that the tube body (3) is in the form of an extrude and in its wallhas a plurality of axially continuous channels (19), distributed aboutthe periphery of the receive space (5), one such channel forming thecavity (16).
 13. The linear drive as set forth in any one of the claims1 through 12, characterized in that the electrical lead means (35) ofthe sensor (14) are in the form of plug means.
 14. The linear drive asset forth in any one of the claims 1 through 13, characterized in thatthe sensor (14) has an essentially L-like configuration, the longer limb(32) extending into the cavity (16) and the shorter limb (33) beingprovided on the rear end section (21) and extending through thelaterally aligned section (28) of the recess's opening (26).
 15. Thelinear drive as set forth in claim 14, characterized in that theelectrical lead means (35) are provided on the shorter limb (33) of thesensor (14).
 16. The linear drive as set forth in any one of the claims1 through 15, characterized in that the sensor (14) has light producingdisplay means (48), same being placed at the rear end section (21). 17.The linear drive as set forth in claim 16, characterized in that thesensor (14) possesses a housing (52) which is transparent at least atthe rear end section (21), through which the light signal of the lightproducing display means (48), enclosed by the housing (52), may be seenfrom the outside.
 18. The linear drive as set forth in any one of theclaims 1 through 17, characterized by a fluid operated design, the drivepart (7) being in the form of an axially sliding piston.
 19. The lineardrive as set forth in any one of the claims 1 through 18,, characterizedin that the housing cover on both end side faces of the tube body (3),such housing cover having at least one recess (22) for a sensor.